1. Field of the Invention
The present invention relates to a siphon-jet flush water supply system for controlling the supply of flush water to a toilet bowl.
2. Description of the Related Art
FIG. 1 of the accompanying drawings shows a conventional flush toilet with a siphon-jet flush water supply system. Flush water supplied from an external water supply pipe (not Shown) through a flush valve is ejected from a jet hole 101 into a pool W of water in a toilet bowl as indicated by the arrow A. The flush water ejected from the jet hole 101 produces a siphon flow as indicated by the arrow B in a siphon drain passage 102, draining the sewage together with the flush water out of the toilet bowl. The conventional siphon-jet toilet is widely used because no odor is given off as the sewage sinks in the pool W of water and the sewage can be discharged by a relatively small amount of water.
It is recognized that the flush water should be supplied under a pressure of 0.7 Kgf/cm.sup.2 in order to produce a sufficient flush water jet from the jet hole 101. Therefore, the conventional siphon-jet flush water supply system cannot be employed on higher floors of tall buildings because the available flush water supply pressure is too low on those floors.
The external water supply pipe for supplying flush water to the conventional siphon-jet flush water supply system on lower floors of tall buildings should be relatively large in diameter for avoiding a pressure loss, and hence its layout is relatively difficult to design.
Another typical flush toilet design employs a water tank for temporarily storing flush water from an external water supply, which may be of a relatively low water pressure. Flush water is introduced into the flush toilet under the pressure of the flush water stored in the water tank. Once the flush water is fully discharged out of the water tank, the toilet cannot be flushed again until the water tank is filled with flush water. Therefore, the flush toilet cannot be continuously flushed. Because the toilet bowl requires at least 8 liters or more of flush water to flush with, the water tank is of a relatively large size and cannot be incorporated in the toilet stool, The water tank makes the entire toilet assembly poor in appearance, and also presents an obstacle to efforts to clean the toilet stool. As used throughout the remainder of the application, the term "toilet stool" is meant to encompass not only the toilet stool of a flush toilet with a siphon-jet flush water supply system, but also the toilet stool together with the separate large storage water tank.